Process for continuous rectification of crude methyl alcohol



May 19, 1931. 1,805,559

PROCESS FOR CONTINOUS RECTIFICATIN OF CRUDEMETHY'L ALCOHOL E. BARBET Filed Deq.

L Som rm v mj Sow.

Patented May` 19, 1931 UNITED STATI-:s

EMILE All'(-lUS'lJIVIlll BAR-BET, OF PAIS, FRANCE PROCESS F013. CONTINUOUS RECTIFICATION OF CRUDE METHYL ALCOHOL Application led December 22, 1925, Serial No'. 77,080, and in AFrance December 22, 1924;

A The crude wood 'alcohol obtained in the carbonization of wood is a very complex mixture, the reining of which to obtain its principal components in a state of purity is a dif- Jl ficult and complicated process.

The object of the present invention is to provide an improved process for the treatf vice e and part of it is returned by way of ment of crude wood alcohol. y

rlhe process according to the invention comlGprises essentially bringing the same at a high concentration and freed from tar in a continuous manner into contact with a stream 'of caustic alkaline lye in which the alcohol will dissolve and the acetone remain insoluble, permitting the aqueous material and the acetone to separate, and continuously and separately withdrawing the acetone and aqueous material in which alcohol is dissolved and subjecting the aqueous material to a continu-- 2@ ous distillation process to recover the wood alcohol therefrom, continuously rectityiug the wood alcohol thus recovered and subject'- ing the acetone to continuous distillation and rectication steps.

ln the rst place it is important that the crude wood alcohol treated shall be of high alcohol content, being atleast 909 Gay Lussac and preferably even more concentrated. lf, therefore, the crude material to be treat- 39 ed is weaker than 90 Gay Lussac it should be lirst subjected to a preliminary concentration.

The invention will be described in detail with reference to the accompanying drawing, illustrating by way of example suitable apparatus for carrying the invention into eifect. The crude wood alcohol contained in the cistern B is delivered by way of the iloat regulator vand the pipe l and at a-rate regulated by means of the cock AC through the inlet 2 into the heat exchanger D from which it passes through the pipe ST4 into the plate column A-A. V

ln the lower section A of this column materials less volatile than water are vaporized, the residual water' passing by way of the inverted Siphon 5 6v into heat exchanger D where the heat contained in the residual liq- 0 uor is given up to the crude wood alcohol tobe treated and from which the cooled residual water is discharged by way ot the pipe 7.

The vapours of acetone and methyl alcohol ing by way of the pipe 8 into the cooler andcondenser E.

vare rectified in A', the rectilied vapours pass- The condensate passes out through the de-4 1 the pipe 11 to thecolumn A in which it forms a reilux, the remainder being highly concentrated wood alcohol passes by way of the pipe 9-10 into the testing gauge F.

The rectified wood alcohol saturated with Aacetone is treated cold with caustic soda lye` of strength between 28 and 30 Baume and in which acetone is insoluble whereas methyl alcohol is soluble. 5

Thisoperation can be elected by any suitable device adapted to bring the lye and wood alcohol into intimate contact but the operation is best carried out in a continuous washer as shown at J. 1

The washing in this device is eii'ected'by causing the alcohol and lye to ilow in counter current, the alcohol entering at the bottom by way of the pipe 12-13 and the soda lye by way oi the pipe 15. Intimate contact of the two liquids is secured in this device with the aid of suitable packing or iilling,

for instance crushed quartz or porcelain balls, with which the washer is charged.

The soda lye is introduced into the washer from the tank N, being drawn therefrom through the pipe-25 by the pump P and delivered through the pipe 2(3 27 into the upper cistern G tted with a float regulator g. From this cistern the lye passes by way of the pipe 14 at a rate controlled by the testing, gauge H and the pipe 15 into the washer il.

Under the influence of the lye, acetone rises in .l and lioats on the surface of the body of the lye' in the upper part thereof. The acetone leaves by'way of an internally 'arranged overflow and passes into the testin gauge K and thence to the acetone recti er subsequently described. .The soda lye containing in solution the vmethyl alcohol is discharged from the base pipe 17 Ato the distilling apparatus by which he methyl alcohol is separated from the soda ye.

The lye containing methyl alcohol in solution is delivered by the pipe 17 by way of the inlet 18 into a tubular heat interchanger m in which it is heated by the rectified or eX- tracted lye delivered thereto by way of the inverted Siphon 22 and after passing in series through the heat interchanger m', the pipe 23 and heat interchanger m it is delivered to the tank N. The lye containing methyl alcohol preheated in the heat interchanger m passes by way of the pipe 19--20 into the top of the plate column M and descends therethrough in the usual way in which at the same time it is heated by means of heat supplied from m to such a degree as will ensure that the regenerated lye is restored to its ori inal concentration. t

he methyl alcohol vapour from the column M passes by way of the pipe 28 to the continuous rectifier of a current type comprising a continuous distillation column OO with a reflux condenser andcooler Q, and a rectifier, properly so called, SS with its reflux condenser and cooler T. y The most volatile fraction containing aldehyde, a small amount of acetone and methyl acetate is delivered by Way of the pipe 30 to the testing gauge R. This product will normally be returned to the crude methyl alcohol in order that it may be again treated wlth soda lye.

The testing gauge V receives the pure and finall rectified methyl alcohol from the rectifier S previously cooled after it has passed through the refrigerator U.

With the apparatus described means (not shown) may be associated for the separation of allyl alcohol, acetone oil and the like.

The crude acetone passing through the testing gauge K is composed of light, medium and heavy elements and it is rectified in the continuous rectifier WW', passing thereto by Way of the pipe 34 and through the heat regenerator w in which its tem erature is raised by the heat contained in t e residual water discharged from the base of W, the preheated acetone passing rom the heat regenerator by way of the ipe 35 into the said rectifier. A reflux con enser and cooler X is associated with this rectifier adjacent to the base of which a tubular heater W is provided. From the head of WW the vapours of acetone are delivered to the cooler X from which by way of the pipe 7 the purified liquid acetone passes to the testing gauge Y` the ethyl methyl acetone asses out through the testing gauge Z and rom the outlet of the recuperator the acetone oils pass out by way of the pipe 39.

In conclusion it may be mentioned that the soda lye used can be used repeatedly until it becomes saturated with sodium acetate formed by the decomposition of the acetic esters present in the crude wood alcohol when it can be treated for the recovery of sodium.

uble, separating the acetone from the caustic alkali of methyl alcohol, se aratin b continuous distillation the met yl alco o from the caustic soda and rectiying the alcohol obtained for collecting on the one hand the pure methyl alcohol and on the other hand separating the products entrained therewith, the separated alkaline solution being again brought into contact with the crude methyl alcohol, the crude acetone separated from the crude methyl alcohol being submitted to a continuous rectification whereby it is possible to obtain the acetone in the state of purity, and separately recovering the products entrained therewith.

4In testimony whereof I have signed my name to this s ecification.

EMIL AUGUSTIN BAR-BET. 

